Vehicles may employ powertrain systems that generate propulsion power from an internal combustion engine (engine) in conjunction with a non-combustion motor such as one or multiple high-voltage electric motor/generators. The high-voltage electric motor/generator(s) draw electric power from an on-vehicle high-voltage electric energy storage device, e.g., a high-voltage battery, via a high-voltage electric power circuit. The high-voltage battery may be charged during vehicle operation, and/or may be charged using electric power sourced from an off-vehicle electric source.
High-voltage batteries may support critical vehicle operations. There may be a need to supply electrical power to critical vehicle operations in the event of a fault in a cell of a high-voltage battery, including supplying electrical power to critical vehicle operations in vehicles that do not employ secondary low-voltage battery backup systems.